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Detection and characterization of a 5HT 1D serotonin receptor‐gtp binding protein interaction in porcine and bovine brain
Author(s) -
HerrickDavis Katharine,
Titeler Milt
Publication year - 1989
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.890030405
Subject(s) - radioligand , 5 ht receptor , receptor , chemistry , binding site , striatum , serotonin , gtp' , radioligand assay , 5 ht1 receptor , gtpgammas , biophysics , g protein , biochemistry , biology , endocrinology , dopamine , enzyme
Radioligand binding studies were performed to characterize serotonin 5HT 1D binding sites in porcine and bovine brain. 3H‐5HT binding, in the presence of 1 μM (+/−)pindolol (to block 5HT 1A and 5HT 1B receptors) and 100 nM mesulergine (to block 5HT 1c receptors), was specific, saturable, and of high affinity. In porcine and bovine cortex and striatum the majority of 5HT 1 sites (80%‐90%) were of the 5HT 1D subtype. In competition experiments 8‐OH‐DPAT, TFMPP, mesulergine, DOB, and ICS 205‐930 had low affinity for 3H‐5HT‐labeled 5HT 1D sites, indicating that the pharmacology of the 5HT 1D site is distinct from previously identified 5HT 1A , 5HT 1B , 5HT 1C , 5HT 2 , and 5HT 3 sites. Guanyl nucleotides, GTPgammaS, and Gpp(NH)p, and divalent cations potently modulated the binding of 3H‐5HT to 5HT 1D sites in porcine and bovine striatum. Mg + + ions increased the number and affinity of 3H‐5HT‐labeled 5HT 1D sites, while guanyl nucleotides decreased the number of 3H‐5HT‐labeled 5HT 1D sites. These results demonstrate the presence of the 5HT 1D receptors in porcine striatum and bovine cortex and provide direct demonstration that the radioligand binding assay for the 5HT 1D receptor can monitor the interaction of this receptor with a GTP‐binding protein.